A critical problem in underground mining operations has always been the problem of circulating fresh air to a mining location and exhausting polluted and dust-ridden air. In present operations, air is conveyed to and exhausted from a mining location by temporary ductwork. In general, mining operations must be discontinued temporarily while the ventilation system is advanced.
As mining operations proceed, the excavation location advances. As a result, the intake for fresh air becomes more and more distant from the excavation site. At times, the ventilation ductwork must be advanced by adding additional sections onto the existing ductwork. In order for ductwork sections to be added safely and without interference, mining operations are stopped temporarily while ventilation ductwork is put in place. Normally, this procedure involves moving in large segments of metal ductwork, bolting them in place and placing some form of gasket around the joint to assure a certain degree of air tightness.